Fixed range indicating system for use in a vehicle travel path indicating apparatus

Abstract

An improved fixed range or distance indicating system for use in a visual travel route indicating apparatus of a vehicle. The fixed range indicating system minimizes memory capacity by discretely storing locational data obtained from discrete arithmetical calculation made at a suitable predetermined interval to present relatively short vector segments optimized in accordance with the given scale of indication on the display and at the same time provides a relatively high accuracy in approximating a current locational indication of the vehicle. A plurality of basic scales of indication varying with doubled denominators in accordance with a given variety of basic scales of indication are presented, the locational data are picked-up discretely at a rate corresponding to the plurality of basic scales of indication, and the thus picked-up locational data is stored into prescribed memory tables within a given limit of indication by way of an endless store mode. The current indicated path of travel on the display is erased at the interval of a fixed range travelled by the vehicle corresponding to the basic scales of indication, and refreshed points of indication are determined for a new location of the vehicle in accordance with a given scale of indication from the current points of indication for the current location at the time of erasing on the basis of the locational data read out from the memory table.

We claim: 
     
       1. A fixed range indication system for use in a vehicle travel path indicating apparatus, comprising: a pulse generator for generating a pulse at every moment when the travel distance of the vehicle increases by a predetermined first distance ("1");   counter means for counting said pulse;   a bearing detection unit for generating a bearing signal (θ) corresponding to the heading of the vehicle;   arithmetic operation means for receiving said bearing signal (θ), arithmetically obtaining a variation of the location of the vehicle on the two-dimensional coordinates from said first distance ("1") and said bearing signal (θ) at every moment when receiving said pulse, and accumulating said variation of location to obtain and output a locational data of the vehicle which is updated at every moment when receiving said pulse;   data extractor means for reading out the number registered in said counter to detect the travel distance of the vehicle and extracting the locational data from the outputs of said arithmetic operation means at every moment when the travel distance of the vehicle increases by a predetermined second distance (d) which is greater than said first distance ("1");   scale selector means for selecting one scale of the indication of the travel path from a plurality of predetermined scales of the indication and generating a selection signal indicating a selected scale;   data selector means for selecting the locational data from all of said extracted locational data at each rate predetermined in accordance with each said scale of the indication, the locational data selected for each said scale of the indication forming a data group, respectively, each said data group being discretely output from said data selector means;   data storing means including a plurality of data tables each adapted for storing one of said data groups and a storing system for storing each of said selected locational data in said data table as a data fraction in the manner of endless memory mode;   data reading means for reading out the number registered in said counter to detect the travel distance of the vehicle, receiving said selection signal, and reading out said data fraction from said memory table for said selected scale to output said data fraction at every moment when the travel distance of the vehicle increases by a fixed range predetermined in accordance with said selected scale, said fixed range being greater than said second distance (d);   data restoring means for restoring a locational data based on said data fraction output from said reading means; and   display means for receiving said restored locational data and indicating the vehicle travel path on a screen in accordance with said restored locational data.